Sinister House — Caroline Farr

Mansion of Madness. When handsome Paul Acton asked her to marry him, it was the happiest day in Samantha Walton's life. Yet Samantha couldn't know that her love for Paul would soon lead her along a mazelike road of evil deceit to Finisterre -- the prisonlike mansion now owned by the Actons but once a home for the hopelessly insane.

Samantha didn't want to be separated from Paul at all, but when he received an excellent job offer, his mother asked Samantha to come to Finisterre. There she wouldn't be as far from Paul and at the same time could help the family by putting their collection of rare books in order. And so Samantha entered the Acton mansion, little realizing that once she passed between its high, forbidding gates she might never leave again...